Compact light weight autothermal reformer assembly

ABSTRACT

A fuel gas-steam reformer assembly, preferably an autothermal reformer assembly, for use in a fuel cell power plant, includes a catalyst bed which is formed from a cylindrical monolithic open cell foam body. The foam body is preferably formed from a high temperature material such as stainless steel, nickel alloys and iron-aluminum alloys, or from a ceramic material. The foam body includes open cells or pores which are contained within the metal or ceramic lattice. The lattice is coated with a porous wash coat which serves as a high surface area substrate onto which catalysts used in the reformer are applied. The foam body has an inlet end into which a mixture of fuel, steam and air is fed to begin the reforming process. An inlet portion of the foam body may be provided with an iron oxide and/or noble metal catalyst and the remainder of the foam body may be provided with a nickel and/or noble metal catalyst. An advantage of including an autothermal reformer in a fuel processing system is the compactness of the autothermal reformer. The inclusion of the foam catalyst bed rather than the traditional catalyzed pellet bed allows the reformer to be made even more compact and light weight.

This is a continuation of a application Ser. No. 09/321,390, filed 27May 1999, now U.S. Pat. No. 6,797,244.

TECHNICAL FIELD

This invention relates to a fuel gas steam reformer assembly. Moreparticularly, this invention relates to an autothermal fuel gas steamreformer assembly which employs an open cell foam catalyst bed thatreduces the size and weight of the reformer assembly.

BACKGROUND ART

Fuel cell power plants include fuel gas steam reformers which areoperable to catalytically convert a fuel gas, such as natural gas orheavier hydrocarbons, into the primary constituents of hydrogen andcarbon dioxide. The conversion involves passing a mixture of the fuelgas and steam through a catalytic bed which is heated to a reformingtemperature which varies depending upon the fuel being reformed.Catalysts typically used are nickel catalysts which are deposited onalumina pellets. There are three types of reformers most commonly usedfor providing a hydrogen-rich gas stream to fuel cell power plants.These are a catalytic steam reformer, an autothermal reformer, and acatalyzed wall reformer. In addition, hydrocarbon fuels may be converteda hydrogen-rich gas stream by use of a partial oxidation reactionapparatus. A typical catalytic steam reformer will consist of aplurality of reaction tubes which are contained in a housing that isinsulated for heat retention. The reaction tubes are heated by burningexcess fuel gas in the housing and passing the burner gas over thereaction tubes. The reforming temperature is in the range of about 700°F. to about 1,600° F. The individual reaction tubes will typicallyinclude a central exhaust passage surrounded by an annular entrypassage. The entry passage is filled with the catalyzed alumina pellets,and a fuel gas-steam manifold is operable to deliver the fuel gas-steammixture to the bottom of each of the entry passages whereupon the fuelgas-steam mixture flows through the catalyst beds. The resultant heatedmixture of mostly hydrogen and carbon dioxide gas then flows through thecentral exhaust passages in each tube so as to assist in heating theinner portions of each of the annular catalyst beds; and thence from thereformer for further processing and utilization. Such catalytic steamreformers are described in U.S. Pat. No. 4,098,587

A typical autothermal reformer may be a single bed or a multiple bedtubular assembly. Autothermal reformers are often used when higheroperation temperatures are required for the reforming process becausethe fuel to be processed is more difficult to reform. In an autothermalreformer, the reaction gasses are heated by burning excess fuel withinthe reaction bed by adding air to the fuel and steam mixture so that theremaining fuel-steam mixture is increased to the temperature necessaryfor the fuel processing reaction.

Typically, wall temperatures in an autothermal reformer are in the rangeof about 1,400° F. to about 1,800° F. Such reformers are described inU.S. Pat. No. 4,473,543.

A third type of prior art reformers have utilized catalyzed wallpassages such as described in U.S. Pat. No. 5,733,347. Such reformersare formed from a sandwich of essentially flat plates with interveningcorrugated plates which form reformer gas passages and adjacentregenerator-heat exchanger passages. Each of the reformer passage plateunits is disposed directly adjacent to a burner passage plate unit sothat the adjacent reformer and burner passages share a common wall.

Besides the reformer devices described above, a partial oxidationreaction apparatus may also be used to produce a hydrogen-rich fuelstream. This device is typically a chamber that is fed a hydrocarbonfuel, steam and oxidant source, usually air, so that the mixturespontaneously partially oxidizes to form a hydrogen-rich mixture. Suchdevices, for example, are disclosed in PCT application WO 98/08771.

U.S. Pat. No. 4,451,578, granted May 29, 1984 contains a discussion ofautothermal reforming assemblages, and is incorporated herein in itsentirety. The autothermal reformer assembly described in the '578 patentutilizes catalyzed alumina pellets. Although autothermal reformers allowa degree of system compaction, it would be desirable to further decreasethe size and weight of an autothermal reformer, and also of any tubularreformer, particularly in systems which are utilized in vehicularapplications. Attempts have been made to decrease the size and weight ofautothermal and other tubular reformers through the use of speciallyconfigured catalyst pellets. Such specialized pellet configurationsinclude rings, flat pellets with holes, wagon wheel-shaped pellets, andlobed pellets, for example.

It would be desirable to provide an autothermal reformer assembly whichdoes not require the use of specially configured catalyzed aluminapellets, and which is more compact and light weight than the prior artautothermal reformer assemblies which do utilize catalyzed aluminapellets. Such reformer assemblies would find particular utility invehicular applications.

DISCLOSURE OF THE INVENTION

This invention relates to a fuel cell system autothermal reformerassembly which provides an enhanced catalyst and heat transfer surfacearea; is compact and light weight; and provides an enhanced gas mixingand distribution flow path. The catalyst bed structure of this inventionis formed from a monolithic open cell foam core which is provided with aporous high surface area wash coat layer onto which the catalyst layeris deposited. The wash coat may be alumina, lanthanum-stabilizedalumina, silica-alumina, silica, ceria, silicon carbide, or another highsurface ceramic material. The choice of wash coat will depend on theoperating parameters of the specific catalyst bed.

The monolithic gas flow component is a foam with interconnected opencells, the surfaces of which are catalyzed with a catalyst. The foammonolith has an entry end portion which is coated with a catalystconsisting of lanthanum-promoted alumina, calcium oxide, and an ironoxide catalyst which can also be treated with a small amount ofplatinum, paladium or rhodium for improved low temperature fuel gasignition. As an alternative configuration, the entry end may include acatalyst of platinum, paladium or rhodium without the iron oxidecatalyst. The remainder of the foam monolith is provided with a nickel,copper or zinc catalyst, or with such noble metal catalysts such asplatinum, palladium, rhodium, or the like. The open cell foam, once washcoated, provides the high surface area base required in order to achievethe deposition of the high surface area catalysts needed to properlyprocess the fuel gas. The open cell foam also provides an enhancedmixing and distribution gas flow pattern for gases passing through themonolith since the gases will flow both laterally and longitudinallythrough the structure. The open cell foam also provides high surfacearea heat transfer paths that contribute to a more turbulent gas flowthat enhances heat transfer rates in systems utilizing the catalyst bed.Additionally, the high heat transfer provided by the foam can becontinued into and through adjacent walls of the reactor so as to createa highly efficient heat transfer device that results in improved processtemperature control and reduces the size and weight of the reformer fora given output level. The intervening walls may be flat plates or theymay be cylindrical walls with heat transfer capabilities. The monolithicopen cell foam catalyst bed may be bonded to the reformer catalyst bedwalls by brazing, or any other appropriate mechanism which is suitablefor the system in question. When a ceramic foam catalyst bed isemployed, the catalyst bed will not likely be bonded to the reformer bedwalls.

All surfaces to be catalyzed will be primed by means of a conventionalwash coating process such as that provided by United Catalyst, W. R.Grace and Co., or Englehard Corp. The wash coating process produces aporous layer on all surfaces of the foam, which layer forms a base forthe catalyst coating. It will be understood that the interstices as wellas the outside surfaces of the open cell foam monolith are wash coatedand are also catalyzed. Since the catalyst beds are of minimal size andweight, they are especially suited to vehicular applications where sizeand weight are critically important, and because vehicle applicationsrequire rapid start-up capability that is closely dependent on the sizeand weight of the components. Small, light weight catalyst and reactantbeds can be rapidly heated with a minimum energy input.

In its preferred embodiment, the autothermal reformer assemblage isgenerally cylindrical in configuration, and includes several concentricchambers formed from cylindrical housing walls. The outermost chamber isannular and contains helical fuel/steam, and/or air flow conduits. In analternate configuration, the outermost conduit could contain a steam/airmixture with the fuel being injected into the steam/air mixture justprior to entry into the entry portion of the catalyst bed. A central gasflow chamber is cylindrical and contains a monolithic open cell foamcatalyst bed through which the fuel, steam and air gas streams flow. Thecatalyst bed has two different catalyzed zones, one of which is an inletzone for carbon-free combustion of a small amount of the fuel gas andfor autothermal reforming of the fuel gas, and the other of which is anadiabatic reforming zone. An intermediate annular gas flow chamber isinterposed between the inner gas flow chamber and the outermost chamberand serves to channel the reformed gas stream which issues from thecentral chamber to the outermost chamber.

Heat is generated internally in the reformer catalyst bed due to theaddition of air to the process gas stream, which is a fuel/steammixture. Thus there is no need to spread the reforming catalyst alonglarge heat transfer surfaces as is required with a conventional steamreformer. The use of an open cell foam monolith as the catalyst supportbed can increase the catalyzed surface area of the support bed by afactor of at least three, depending on the pore size of the foamcatalyst support bed. Use of the foam support bed can also reduce thevolume of the bed by a factor of at least three, and can reduce theweight of the bed by an even greater factor, as compared to a pelletizedcatalyst bed. The foam catalyst support bed can provide greater than an80% open volume while a pelletized bed provides about a 40% open volume.The increased open volume results in a much lower pressure drop acrossthe catalyst bed than can be achieved with a pelletized bed.

Start-up of the reformer can be achieved by either pre-heating the bedwith a hot gas, such as steam, or by fabricating either the entiremonolith or just the inlet section with a conductive resistance monolithelement. The resistance element can be connected to an electrical sourcesuch as a car battery which will enable the monolith to reach operatingtemperatures within less than twenty seconds.

An example of the benefits of the foamed catalyst support is that, foran equivalent catalyzed surface area, a pelletized autothermal catalystbed has a volume of 0.25 ft³, weighs about twenty five pounds; while afoam support bed having a twenty pore/inch pore size can be formed witha volume of 0.07 ft³, and weighs less than four pounds. In cases whereina higher pressure drop can be tolerated, a 30 to 40 pore/inch foam canbe used to provide an even small and lighter bed. Such small and lightweight fuel processors can be heated quickly using electricity from anautomobile battery, and thus are particularly desirable for vehicularapplications.

In a preferred embodiment of the invention, the catalyst bed will beformed from a ceramic foam that will be wash coated with alumina,calcium aluminate or lanthanum-promoted alumina, whereafter the washcoat will be impregnated with a proper catalyst. The inlet section ofthe catalyst bed will be provided with an iron oxide catalyst whichlimits carbon deposition and is, at the same time operable to raise thetemperature of the incoming gas stream without requiring large amountsof oxygen as described in U.S. Pat. No. 4,451,578. The iron catalyst maybe promoted with a small quantity of platinum, palladium or rhodium soas to provide a lower ignition temperature of the fuel gas fraction thatis combusted in the reformer during operation of the reformer. In thecase of an autothermal reformer with a conventional catalyst thatincludes iron oxide as described in U.S. Pat. No. 4,451,578, theexpected ignition temperature of the fuel is in the 1,000 to 1,300° F.range. However, it has been found that with the addition of a smallamount of a nobel metal catalyst such as platinum, palladium or rhodiumto the iron oxide, the ignition temperature can be lowered to about 500°F. The nobel metal catalyst addition is in the range of about 0.01% upto about 1.0% by weight. Typically, the amount added is about 0.1%. Theachievement of a lower ignition temperature enables a quicker start-upof the reformer which is particularly desirable in vehicularapplications of the system. The iron oxide in the catalyst could bereplaced by platinum, palladium or rhodium as described in U.S. Pat. No.4,415,484.

The inlet portion of the catalyst bed is operable to burn oxygen and aminor amount of the fuel gas so as to raise the temperature of the inletportion of the catalyst bed. This raises the temperature of the gasstream to temperatures which provide enhanced conversion of the fuelstream to a high hydrogen-content gas. Minimal oxygen requirements serveto inhibit carbon formation in the catalyst bed. Other carbonformation-supressing catalyst bed components such as calcium oxide,lanthanum oxide, and/or cerium oxide, for example, could also be used.The subsequent reforming section of the catalyst bed is provided with aconventional nickel or noble metal reforming catalyst, or a combinationof a nickel reforming catalyst, and a noble metal reforming catalyst.

It is therefore an object of this invention to provide an improvedautothermal fuel gas processing assembly which includes a catalyst bedthat is compact and light weight.

It is a further object of this invention to provide a fuel gasprocessing assembly of the character described which is sufficientlycompact and light weight so as to be useful in a vehicular application.

It is another object of this invention to provide a fuel gas processingassembly of the character described which can be quickly brought up tooperating temperatures through the use of electricity provided by anautomotive battery.

It is yet another object of this invention to provide a fuel gasprocessing assembly of the character described which has a lowered fuelignition temperature to allow rapid start up.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of this invention will becomereadily apparent to one skilled in the art from the following detaileddescription of a preferred embodiment of the invention when taken inconjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a preferred form of an open cellmonolithic foam catalyst bed which is adapted for use in an autothermalor tubular reformer assembly formed in accordance with this invention;

FIG. 2 is an axial cross-sectional view of an autothermal reformerassembly which is formed in accordance with this invention; and

FIG. 3 is a sectional view of the reformer assembly taken along line 3—3of FIG. 2.

SPECIFIC MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, there is shown in FIG. 1 a perspectiveview of a cylindrical form of a catalyst bed formed in accordance withthis invention, which bed is denoted generally by the numeral 2. Thecatalyst bed 2 is a monolithic open cell foam component which includes alattice network of tendrils 4 which form a network of open cells 6 whichare interconnected in the X, Y and Z directions within the bed 2. Itwill be appreciated that the catalyst bed 2 can be formed from a singlemonolith or from a plurality of thinner monoliths stacked one atop theother. The latter approach could simplify the differential catalyzationof the bed 2, and could also reduce thermal stresses imparted to the bed2 during operation of the reformer. The interconnected open cells 6 areoperable to form an enhanced fuel gas mixing and distribution flow pathfrom end 8 to end 10 of the bed 2. The open cells 6 and the tendrils 4also provide a very large catalyzable surface area in the bed 2. Thecore of the foam catalyst bed 2 can be formed from aluminum, stainlesssteel, an aluminum-steel alloy, silicon carbide, nickel alloys, carbon,graphite, a ceramic, or the like material.

The bed 2 is catalyzed in the following manner. A wash coated porousalumina primer is applied to all outer and interstitial surfaces in thebed 2 which are to be catalyzed. The alumina wash coat can be applied tothe bed 2 by dipping the bed 2 into a wash coat solution, or by sprayingthe wash coat solution onto the bed 2. The wash coated bed 2 is thenheat treated so as to form the high surface area porous alumina layer onthe core. The catalyst layer is then applied to the alumina surfaces ofthe bed 2. If so desired, the alumina coating and catalyzing steps canbe performed concurrently. Similar steps could be used for other washcoating materials.

FIG. 2 is a somewhat schematic sectional view of an autothermal reformerassembly denoted generally by the numeral 3 which includes the catalystbed 2 of FIG. 1. The catalyst bed 2 is contained in an open-endedcylindrical inner housing 12, the bottom of which contains a porous meshscreen 14 which supports the catalyst bed 2 and allows the reformed gasstream to exit from the inner housing 12. An intermediate cylindricalhousing 16 surrounds the inner housing 12 and forms an inner annular gasflow path 18 for gas exiting from the catalyst bed 2. An outercylindrical housing 20 forms the outermost wall of the reformer assembly3. The outer cylindrical housing 20 combines with the intermediatecylindrical housing 16 to form an outer annular gas flow path chamber 22in the assembly 3. The bottom of the assembly 3 is closed by a lowerannular wall 24, and the upper end of the assembly 3 is closed by anupper annular wall 26 and a manifold 28. The inner housing 12 can beinsulated to prevent heat loss to the stream in the annulus 18.

The manifold 28 includes an upper fuel/stream-inlet chamber 30 and alower air-inlet chamber 32. The chambers 30 and 32 are separated by aplate 34 having a plurality of passages 36 formed therein. A similarplate 38 forms the lower wall of the air-inlet chamber 32. A pluralityof fuel passage tubes 40 interconnect the two plates 34 and 38, thetubes 40 including perforations 42 which admit air from the chamber 32into the gas stream flowing through the tubes 40. The air and fuel/steamstreams thus intermingle in the tubes 40 before entering the inlet end 8of the catalyst bed 2.

The fuel/steam mixture enters the reformer assembly 3 via a heatexchange tube 44, as indicated by arrow A. The temperature of theincoming fuel/steam mixture is about 450° F. The air stream enters thereformer assembly 3 via a heat exchange tube 46, as indicated by arrowB. The temperature of the entering air stream is similar to thetemperature of the fuel/steam stream. The heat exchange tubes 44 and 46can be finned tubes, or can be covered with a foam material similar tothat shown in FIG. 1 above. The fins or foam are operable to enhanceheat transfer to the gas streams in the tubes 44 and 46.

The heat exchange tubes 44 and 46 both spiral around the cylindricalhousing 16 through the chamber 22 so that heat is transferred to thefuel/steam mixture stream and to the air stream from the reformerexhaust stream, as will be described in more detail hereinafter.Alternatively, the spiral tubes could be replaced by other heatexchanger mechanisms which are capable of transferring energy from theprocessed exhaust gas stream to the inlet streams. By the time that thefuel/steam mixture stream enters the inlet chamber 30, its temperaturewill have been raised to a temperature in the range of about 800° F. toabout 1,100° F., and by the time that the air stream enters the inletchamber 32, its temperature will have been elevated to the sametemperature range. The fuel/steam mixture exits the inlet chamber 30 viathe tubes 40. The air stream B enters the tubes 40 by way of theopenings 42 and intermingles with the gas/steam mixture in the tubes 40.Thus, the proper admixture of air, steam and fuel will be formed in thetubes 40 and will flow therefrom into the inlet end 8 of the catalystbed 2. The temperature of the air, steam and fuel admixture will be inthe range of about 800° F. to about 1,100° F.

The catalyst bed 2 is preferably divided into different catalyst zoneswhich include an initial inlet zone 48 and a subsequent zone 50. Theinlet zone 48 is typically wash coated with alumina and then catalyzedwith calcium oxide, iron oxide, and/or platinum, palladium or rhodium,so as to increase the temperature of the gas mixture to about 1,600° F.to about 1,900° F., about 1,760° F. being the preferred temperature, bycombustion or partial oxidation of the in-coming fuel/steam/air mixture.

The subsequent catalyst zone 50 is provided with an underlying wash coatof alumina which is overlain by a nickel or noble metal catalyst. Thecatalyst zone 50 is operative to convert the fuel/steam and air mixtureinto a hydrogen-enriched fuel stream suitable for use in a fuel cellpower plant. The core of the foam catalyst bed 2 in the zone 50 can beformed from stainless steel, an aluminum-steel alloy, silicon carbide,nickel alloys, carbon, graphite, a ceramic, or the like material. Thebed 2 is catalyzed in the following manner. A wash coated porous aluminaprimer is applied to all outer and interstitial surfaces in the bed 2which are to be catalyzed. The alumina wash coat can be applied to thebed 2 by dipping the bed 2 into a wash coat solution, or by spraying thewash coat solution onto the bed 2. The wash coated bed 2 is then heattreated so as to form the alumina layer on the core. The catalyst layeris then applied to the alumina surfaces of the bed 2. If so desired, thealumina coating and catalyzing steps can be performed concurrently.Similar steps could be used for other wash coating materials.

The reformed fuel stream exits from the catalyst bed 2 through thescreen 14 at a temperature of about 1,100° F. to about 1,400° F. andthen passes upwardly through the annulus 18 per arrows C. The exit gasfrom the reformer passes up through the annulus 18 in order to provideheat to the incoming fuel/steam mixture and the incoming air stream heatexchange tubes 44 and 46. The reformed gas then continues to supply heatto these tubes as it travels through the chamber 22 to the exit passage52. The reformed gas stream exits the assembly 3 through the passage 52at a temperature of about 700° F. to about 1,100° F. whereupon it isfurther cooled and then passes to a shift converter in the fuel cellpower plant assembly.

As noted in FIG. 3, the fuel/steam and air transfer and mixing tubes 40are arranged in a generally circular array through the plate 34 in themanifold 28. The number of tubes 40 can be varied as necessary,depending on the desired flow rate of the reformed fuel through theassembly 3, and the desired air-fuel-steam mixing ratios.

The open cell foam catalyst bed structure provides improved heattransfer, improved gas flow characteristics, and maximized catalystsurface area. The weight and size reductions achieved by using thecatalyst bed construction of this invention are necessary for use insmaller applications such as in mobile vehicles, due to their smallersize and weight. Small size and weight also allow for rapid catalyst bedheat-up to operating temperatures which is a critical requirement forquick start capability necessary in most vehicle applications. Thereduced size and weight will also benefit the packaging of stationarypower plants. The catalyst bed can be formed from a single monolithcore, or can be formed from a plurality of the monolith cores in theform of discs which are stacked one atop another. Monolith cores of thetype described above can be obtained from Porvair Advanced Material,Inc., Hendersonville, N.C.

Since many changes and variations of the disclosed embodiment of theinvention may be made without departing from the inventive concept, itis not intended to limit the invention other than as required by theappended claims.

1. A hydrocarbon fuel gas autothermal reformer assembly comprising: a) amonolithic open cell foam core catalyst bed, said catalyst bed includingan inlet end and an outlet end, an inlet portion of said catalyst bedbeing provided with a catalyst which is operable to combust a portion ofthe fuel gas so as to raise the temperature of said catalyst bed whileminimizing carbon deposition in catalyzed cells of said foam core, saidfoam core catalyst bed including a high temperature-compatable metalsupport selected from the group consisting of stainless steel, nickelalloys and iron-aluminum alloys, and said catalyst bed further includinga noble metal and calcium oxide; b) a fuel gas inlet passage, said fuelgas inlet passage being disposed in heat exchange relationship with anoutlet processed fuel gas passage from said catalyst bed whereby heatwill be transferred to said fuel gas inlet passage from the processedgas stream; c) an air inlet passage, said air inlet passage beingdisposed in heat exchange relationship with processed gas stream wherebyheat from the processed gas stream will be transferred to said air inletpassage; and d) a fuel gas reforming catalyst deposited in said foamcore catalyst bed.
 2. The autothermal reformer assembly of claim 1wherein said foam catalyst bed comprises at least two catalyzed regionswherein each region has a different catalyst composition.
 3. Theautothermal reformer assembly of claim 2 wherein a first region of saidfoam catalyst bed contains a noble metal catalyst in combination withcalcium oxide.
 4. The autothermal reformer assembly of claim 3 wherein asecond region of said foam catalyst bed contains a base metal catalystin combination with calcium oxide.
 5. The autothermal reformer assemblyof claim 4 wherein said first region of said foam catalyst bed containsa platinum catalyst, and said second region of said foam catalyst bedcontains a nickel catalyst.
 6. The autothermal reformer assembly ofclaim 3 wherein said first region of said foam catalyst bed contains aniron oxide/calcium oxide catalyst mixture and said second region of saidfoam catalyst bed contains a nickel catalyst.
 7. The autothermalreformer assembly of claim 3 wherein said noble metal catalyst is acatalyst selected from the group consisting of platinum, palladium andrhodium, and mixtures thereof.
 8. The autothermal reformer assembly ofclaim 1 wherein said foam catalyst bed includes a first region whichcontains a noble metal catalyst and a calcium oxide catalyst, and asubsequent region which does not contain calcium oxide and does containsaid noble metal catalyst.
 9. The autothermal reformer assembly of claim8 wherein said noble metal catalyst is selected from the groupconsisting of platinum, palladium and rhodium.
 10. The autothermalreformer assembly of claim 1 wherein said foam catalyst bed includes atleast one ceramic foam support body.
 11. The autothermal reformerassembly of claim 1 wherein said catalyst bed is cylindrical in shape.12. The autothermal reformer assembly of claim 1 wherein said fuel gasinlet passage contains a fuel gas/steam mixture.
 13. The autothermalreformer assembly of claim 1 wherein said air inlet passage contains anair/steam mixture.
 14. A hydrocarbon fuel gas autothermal reformerassembly comprising: a) a cylindrical monolithic open cell foam catalystbed, said foam catalyst bed including a metal support selected from thegroup consisting of stainless steel, nickel alloys and iron-aluminumalloys, said catalyst bed including an inlet end and an outlet end; b) afuel gas/steam mixture inlet passage; and c) a fuel gas reformingcatalyst deposited in said cylindrical foam catalyst bed.
 15. Ahydrocarbon fuel gas autothermal reformer assembly comprising: a) amonolithic open cell foam catalyst bed, said foam catalyst bed includinga metal support selected from the group consisting of stainless steel,nickel alloys and iron-aluminum alloys, said catalyst bed including aninlet end and an outlet end, an inlet portion of said catalyst bed beingprovided with a noble metal-promoted catalyst which is operable tocombust a portion of the fuel gas at a temperature of about 500° F.thereby enabling start up of the reformer assembly while inhibitingcarbon deposition in catalyzed cells of said foam; b) a fuel gas inletpassage, said fuel gas inlet passage being disposed in heat exchangerelationship with a processed fuel gas stream disposed in an outletpassage from said catalyst bed whereby heat will be transferred to saidfuel gas inlet passage from the processed gas stream; c) an air inletpassage, said air inlet passage being disposed in heat exchangerelationship with processed fuel gas stream whereby heat from theprocessed fuel gas stream will be transferred to said air inlet passage;and d) a fuel gas reforming catalyst deposited in said foam catalystbed.
 16. A hydrocarbon fuel gas autothermal reformer assembly comprisinga monolithic open cell foam catalyst bed, said foam catalyst bedincluding a metal support selected from the group consisting ofstainless steel, nickel alloys and iron-aluminum alloys, said catalystbed including an inlet end and an outlet end, an inlet portion of saidcatalyst bed being provided with a noble metal-promoted catalyst whichis operable to combust a portion of the fuel gas at a temperature ofabout 500° F. thereby enabling start up of the reformer assembly whileinhibiting carbon deposition in catalyzed cells of said foam catalystbed.